Multiple tank fuel system



Sept. 3, 1946.. D. SAMIRAN 2,406,854

MULTIPLE TANK FUEL SYSTEM- Filed Feb. 12, 1943 3., Sheets-Sheet 2 WQILIIIII Ill 48 35 4/ 3 ./7 OUT 5 6. Pump 90X. PU

Patented Sept. 3, 1946 UNITED STATES PATENT OFFICE 9 Claims.

amended April 30, 1928; 370 0. G. 757) The invention described herein may be manu- Referring to Fig. 2, which shows an enlarged factured and used by or for the Government for longitudinal cross section through one of the solegovernmental purposes, without the payment to noid-operated valves, the flow between the inlet me of any royalty thereon. 39 and the outlet 32 is controlled by a valve disk This invention relates to fuel systems and has 33 which is lifted 'to open position by a soleparticular reference to systems employing a plunoid core 36, which is in turn lifted by coils 38 rality of fuel tanks such, for instance, as the and 4G. The coil 38 is wound of relatively coarse system on an aircraft. wire and few turns, While the coil 40 is wound An object of the invention is to provide a fuel of finer wire, the intention being to apply a heavy system of this character with means to maintain current to the coil 38 to lift the valve disk from 1e pressure in the fuel line substantially conits seat, then discontinue the heavy current in the stant while changing the connection of the succoarse wire coil .38 and apply a small current to tion side of the fuel pump from one t nk to the fine wire coil 49, to thereby hold the valve in the next as successive tanks are emptied. p DOSitiOn W a minimum expenditure 0 Another object is to provide power-operated r y- A solenoid-controlled v lve, ch a is means to chang the connections of th fuel lOWIl in Fig. 2, will be described and claimed in' pump, which extend to the fuel tanks, from an a p e pp o f which I am joint nempty to a full tank, with means for automati- Ve to cally sensing the fact of an empty tank and apply- A fuel discharge pipe 42 extends from the main ing the power means for making the change, then fuel pump l2 to the bottom of an air separator disconnecting the power means after the change 44, the outlet pipe 46 of which delivers fuel to is made. the carburetor Id. The pump I2 is of the type Another object is to provide manually selective having a built-in relief valve such as is shown means for quickly connecting to any one of the at 57 in the enlarged View, 5 being thereby several tanks, independently of the power means, 5 adapted to maintain a g en pressure p the when that becomes desirable. relief valve in this pump being adjusted to deliver Other objects and advantages will be readily fuel to the outlet at fifteen pounds pressure. perceived by a study of the following description A float 48 in the top of the air separator is so with reference to the drawings, wherein: loaded as to permit the discharge of vapor from Fig. l is a schematic view of a fuel system made the top of the separator to the tops of the tanks according to my invention; through a pipe 50 when the amount of accumu- Fig. 2 is an enlarged View of the solenoid-operlated vapor in the top of the air separator forces ated valves of Fig. 1 shown in detail; the liquid fuel down to a predetermined level.

Fig. 3 is an enlarged vertical axial section The air separator is unique in that it is arthrough-the air eliminator of Fig. 1; ranged to receive the fuel dischargedfrom both Fig. 4 is an enlarged vertical axial section the main pump l2 and an auxiliary pump 52 and through a special check valve of Fig. 1; discharge the fuel free from air through a com- Fig. 5 is an enlarged vertical section through mon pipe 46. It is shown in detail to an enlarged either'the main pump or the auxiliary pump of scale in Fig. 3 and comprises an outer vessel Fig. 1; II and a concentric imier vessel 13 secured to- Fig. 6 is an axial section through the powergether so as to leave a space l5 between them operated selective switch for operating the solewhich connects with the opening I! into which noid valves. the engine-driven fuel pump discharges. A con- Similar numerals refer to similar parts centric cone-shaped part I9 is secured at its throughout the drawings. periphery to the inner vessel 13 and a long tubu- Referring now particularly to the schematic lar portion 2| connects to the opening 23 into illustr tio an engine I" C i s a main which an auxiliary fuel pump discharges. The fuel pump E2, the pump being operatively conspace 25 between the vessel I3 and cone l9 connected to the en ine to be rotated thereby, and meets to the outlet opening 21 from which the fuel adapt d to supply fue to a c bu to I A flows to the carburetor through the pipe 46. The manifold it connects the intake side of the fuel flange of a float housing 29 is held between a pump [2 to a series of tanks I to 6, inclusive, cover 3| and an intermediate section 33, leaving thefuel passing through solenoid-operated valves a space 35 between the float housing and the l8 to 28, which control the flow from the tanks intermediate section. Circular rows of small to the pump. holes 31 and 39 connect the spaces I 5, 25, and

35 to each other. The float 48 is guided at the bottom by a tube 4! which fits freely in a hub 43 of the float housing and at the top by a valve needle support l5 which fits freely in a valve seat member .1. The valve needle 43 is resiliently held by a spring 5| extending upward from the bottom of the support 45 which is fastened onto the hub 53 on the upper side of the float, whereby the needle is resiliently seated when the float rises. The sides of the float housing 29 have a plurality of perforations 55.

The auxiliary fuel pump 52 shown to an enlarged scale in Fig. 5 may be connected to either one of the six tanks by a suction pipe 5%, the tank selected. in the instant case, for illustrative purposes, being tank 6. A discharge pipe 58 extends from the outlet of the auxiliary pump to the bottom of the air separator M, whereby fuel from the auxiliary pump also passes through the air separator and through pipe 16 to the carburetor Me. The auxiliary pump is also of the type having a relief valve 51 which maintains a given pressure output, the relief valve 5! in the auxiliary pump being set to deliver fuel under a pressure of ten pounds. An electric motor 58 is provided for operating the auxiliary fuel pump.

Since the relief valve 5! is set to return fuel from the high to the low pressure side at ten pounds pressure, and the engine pump l2 puts fuel into the high-pressure side at fifteen pounds pressure, a check valve 59 is provided to prevent fuel returning from the high pressure side through the auxiliary pump 52 to the tank 5.

Check valve 59 shown in detail in Fig. 4 comprises a casing 6| divided into three compartments63, 65, 6'!by two spaced-apart Sylphon diaphragms 69, compartment 65 being open at 8! to the atmosphere, whereby, since the atmospheric pressure acts in opposite directions on the two Sylphons 69, any change in altitude, and its consequent change in atmospheric pressure, does not affect operation of the valve. A valve head H has its stem 13 sealed to both diaphragms by nuts 89. Valve head H is biased to open" position by the spring 11 which reacts against a partition 19 extending from the casing 6!. Compartment B3 and the space 99 above the relief valve 51 of the auxiliary pump are connected to the pipe 4% by a pipe 9!, whereby the Valve 59 is closed by the pressure in compartment 63 whenever the discharge pressure of the main pump 12 exceeds the discharge pressure of the auxiliary pump 52 by a predetermined amount, and the spring 99 of the relief valve 51 is assisted in preventing leakage backwardly through the auxiliary pump by the same pressure while compartment 61 is connected by a pipe 33 to the pipe 46 through the air separator 44 and to the outlet 56 of the auxiliary pump when the valve 59 is open.

Connected into the high-pressure side of the two fuel pumps above described, by connecting into the pipe 42, is a fuel-pressure-sensitive electrical switch which may be broadly designated by the numeral 15. Switch [5 comprises a body 60 divided into two compartments by diaphragm 62 which is moved in one direction by the pressure in the pipe 42, but urged in the opposite direction by a spring 64 whereby, in the absence of sufficient pressure in the pipe 42, the spring 64 moves a contact bar 65 into engagement with contacts 68 and H1, thereby keeping switch closed as shown in Fig. 1 until the pressure in pipe 42 is restored. The spring 64 is so proportioned that switch 15 closes upon a drop in pressure in the 88 of the auxiliary pump motor 58.

pipe 42 to about twelve pounds. A signal lamp is so connected to the switch terminal 10 as to give warning whenever the switch 15 has reached a closed position.

A second pressure-sensitive switch, which may be broadly designated by the numeral 8!, comprises a body 12 and a contact bar M which is adapted to be moved to connect the contacts 16 and 18. Switch 81 may be supported on the engine ill and is connected to the lubricating oil system by a pipe 83, being responsive to the oil pressure of the engine. The switch 8| is constructed substantially like the switch 15 with respect to the diaphragm and the spring, except that while the application of pressure to the upper surface of the diaphragm of the switch '15 opens it, the application of pressure to the upper surface of the diaphragm of the switch 8| closes it.

A main manual switch Bi! is provided to connect the battery 82 to the post 84. An additional manually controlled switch 85 connects the switch terminal 10 of the switch 15 to the binding post This switch may be used whenever it becomes desirable to stop rotation of the pump motor 58 while the main switch 80 is closed.

An automatic power-operated valve selector 9!] (see Figs. 1 and 6) comprises an electric motor 92 which may preferably have an inbuilt speedreducing gear box of high ratio so that the shaft 94 may operate at greatly reduced speedthat is, the motor 92 may preferably rotate as much as two hundred R. P. M. to one B. P. M. of the shaft 94. A dielectric disk 95 is concentrically supported on the flange 91 of the motor 92, and carries a circular row of twelve electrical contacts, pairs of which are connected to the solenoid-operated valves, contact IL being connected to the lifting coil of valve l8, and contact I being connected to the holding coil of valve [8; contact 2L being connected to the lifting coil of valve 20, and contact 2 being connected to the holding coil of valve 2%; etc. A cam 98 is secured to the shaft 54 to rotate in unison therewith. A contact arm we is loose on the shaft 94 and insulated therefrom by a dielectric bushing 95 but is caused to rotate with the shaft by means of a plunger [02 which is slidable in a dielectric bushing I03 in the end of the arm H30 and has its free end extending into one of the six notches I94. A knob m5 is provided, the knob and the arm H10 both being fast on the bushing 95, whereby the contact arm I09 may be manually rotated in advance of the slow rotation of cam 98 when so desired. A spring I86 maintains the plunger I02 seated in whichever notch it happens to engage.

On the outside of cam 98 are a series of six cam lobes I08 equally spaced around its periphery. A dielectric plunger I Ii) is carried on a metal arm H2 which is hinged at HG to the dielectric disk 96, the free end of this arm being adapted to engage an extension of the binding post H6 of the motor 92. A coil spring H8 urges the arm H2 toward engagement with the binding post extension. The point of contact between the arm H2 and the extension of the binding post H6 serves as a switch which may be hereinafter referred to as the switch I29. Electrical conductors connect the post 84 to the terminal 68 of switch 15, the terminal E0 to its signal light 35, the terminal 70 to the terminal 16, the terminal 18 to the binding 'post i IS, the terminal l'il through the switch 86 to the binding post 88, and the post 84 to the arm H2 and the contact arm I09. I

' ITheoperation of the mechanism is as follows;

If the engine is at rest and no fuel pumps are in operation, the reduced pressure in the body 50 of the switch I5 will have permitted the switch to beclosed as shown, while absence of oil pressure in the engine. I will have permitted the switch 8| to beopened as shown. In order to start the engine, the main switch 80. and the manual switch 86 should now be closed. This will supply current to the binding post 88 of the auxiliary pump motor 58. Rotation of the auxiliary pump 52 will nowbuild up a pressure of ten pounds in the carburetor I4, which is enough to start the engine- The building up of the pressure in this manner should be accomplished before there is any attempt to start the engine. The ten-pound pressure supplied to the carburetor I4 will not, however, operate the switch I tofopen position, inasmuch as this switch is setto open at twelve pounds. As soon, however, as the engine starts, thepump I2, which is set to deliver fuel at fifteen pounds pressure and which is driven by the engine, will operate the switch I5 to open position, while the oil pressure built up by the engine will operate the switch ill to its closed position. As soon as this occurs, current will be cut off from the auxiliary pump motor 58, and the duty of supplying a fifteen-pound pressure to the carburetor I4 will be assumed by the pump I2, the check valve 59 becoming operative to prevent fluid from the pump I2 being pumped in reverse direction through the relief valve 51 of the auxiliary pump 52, and the relief valve 51 being reinforced'against leakage by virtue of the fifteenpound pressure being applied in the space above the relief valve to hold it closed.

Thus far no electric current has as yet been delivered to the binding post II6 of the valve selector motor 92, inasmuch as the switch I5 and the switch 8| have not thus far been closed at the same time; neither has current been delivered to the binding post IIB through the arm II2, since this occurs only when the spring [I8 effects contact of the arm with the binding post, which may not occur until the lobe I08 of the cam moves from under the lobe I III of the arm. The contact arm I00, therefore, up to this time, has main tained the valve I8 in its open position and will continue to so maintain it until current is in some manner supplied to the binding post I I6. 1 When the engine has been in operation for a sufficient time to empty the tank I, the pump I2 will momentarily draw air from the empty tank I and pump it into the pipe 42, which will instantly cause the pressure in the discharge pipe 42 to drop. When it has dropped to as little as twelve pounds, which will be almost instantly, the switch I5 will close, while the previously closed switch 8| remains closed, the air drawn in by pump I2 passing out through the air separator 44. When both switches I5 and 8| are closed, current will flow to the binding post I I6, and the selector motor 92 will begin rotating the cam 98 clockwise, carrying the contact arm I00 with it. As soon as the cam 98 rotates slightly, the lobe I08 moves from under the lobe I I0 and the spring II8 closes the switch I20, after which current will be supplied to the binding post Il6 directly from the post 84 until the next succeeding lobe I08 moves under the lobe IIO, thereby opening the switch I20 and stopping the arm I00 at the desired place.

The above arrangement is highly desirable, for while the arm I00 would continue rotation as long as current wasbeing supplied to the motor 6 92from the ignition post through both switches I5 and BI, the arm could readily stop rotating before it had reached a proper position for holding open the valve 20 of tank 2, since the fuel pump I2 might readilyhave built up a pressure of twelve pounds and opened the switch I5 in advance of a complete movement of the arm I00 through 60 degrees to its next succeeding position. With the arrangement shown, when a tank from which fuel is being pumped becomes empty and air passes through the pump I2, resulting in a drop in pressure on the diaphragm 62, and the pounds up to the instant that the engine-driven pump I2 builds up its pressure to twelve pounds and opens the switch I5, which insures a satisfactory fuel pressure during the entire time that a change-over from an empty to a full tank takes place.

When the next succeeding lobe I08 has raised the lobe He and opened the switch I20, the arm I00 will have passed the contact 2L by which the valve 20 was opened and will now be resting only on the contact 2 by which the valve 20 will be held open. The width of the arm I00 and the size and spacing of the contacts, however, should be such that the arm engages the contact 2 slightly before it leaves the contact 2L, for otherwise the valve would close as soon as the arm left the contact 2L. When change in connection has thus been made between an empty tank I and a full tank 2, no further changes will take place until tank 2 becomes empty. If, however, tank 2 when thus connected was found to be already empty, the selector merely passes over it, since air drawn from empty tank 2 and transferred to pipe 42 would close the switch I5 and move the arm I00 forward to connect the tank 3. Thus the automatic selector will search the entire series of tanks and will not stop until a full one is found, the auxiliary pump meanwhile maintaining a satisfactory fuel pressure until a full tank is found. Such an arrangement is desirable because it may sometimes happen, particularly where the system is used on war craft, that one of the tanks will have been punctured and the fuel lost, in which case it becomes necessary that the selector operate to pass such tank and connect the system to one that is full. As an added measure of safety, I may provide a multipl handoperated fuel valve I22 by which any one of the tanks may be connected to the pump I2 should automatic operation of the selector valve fail. The need for using this 'manual valve would appear upon an extended signal from the light 85.

I claim;

1. The combination, in an aircraft fuel system, of an engine, a main fuel pump driven by said engine, .a plurality of fuel tanks each connected to the suction side of said pump, an electromagnetically operated valve interposed in each of the lines which connect a tank to the pump, a solenoid for holding the valve open, a carburetor connected to the discharge side of said pump, an auxiliary fuel pump having its suction side con nected to one of said tanks independently of the electromagnetically operated valve and having its discharg line connected to the discharge side of said main pump, a check valve in said discharge line biased to prevent flow from the discharge side of the main fuel pump to the dis charge side of the auxiliary fuel pump, an electric motor for driving said auxiliary fuel pump, an electric current source, a switch for connecting said electric motor to said source, a pressure operated means connected to the discharge side of said main fuel pump for holding said switch open by said discharge pressure, a rotatable switch having circumferentially spaced insulated current supplying contacts for directing current to the coils of the electromagnetically operated valves, an electric motor for rotating said rotatable switch, a cam rotatable by said motor, said cam having a series of lobes and a series of detent notches, each corresponding to the number of electrically operated valves, a cam operated switch, successively operable to open position by each of said lobes upon rotation of said cam, a current supplying arm rotatable about the axis of said cam, a detent member carried by said arm for resiliently engaging in any selected one of said detent notches, said notches and said lobes being so spaced on said cam that when the arm engages a valve holding solenoid contact, the cam operated switch is open, electrically conductive means for connecting the current source in parallel through the fuel pressure operated switch and through the cam operated switch to the rotatable switch electric motor, electrically conductive means for connecting the current source to the arm of the rotatable switch, and electrically conductive means for connecting the current source through the fuel pressure operated switch to the auxiliary pump motor.

2. The combination, in an aircraft fuel system, of a plurality of main fuel supply tanks, a main engine driven fuel pump, valves operable to con nect the suction side of said pump to either of said main fuel supply tanks, a reserve fuel supply container, an electric motor driven auxiliary fuel pump having its suction side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, and the main fuel pump being adapted to deliver fuel at a higher pressure than the auxiliary fuel pump, a check valve adapted to prevent flow from the discharge side of said main fuel pump to the discharge side of said auxiliary fuel pump, a pressure responsive switch associated with the main fuel pump, adapted, upon a predetermined drop in pressure at the discharge side of the main fuel pump, due to a tank to which its suction side is connected being empty, to close and direct an electric current to operate said electric motor driven auxiliary fuel pump, and electromagnetic valve operating means operative by said switch upon closing to close the valve of the empty tank and open the valve of the next full tank, whereby said main fuel pump may provide said predetermined pressure to open said pressure operated switch to stop said electric motor driven auxiliary pump.

3. The combination, in an aircraft fuel system, of a plurality of main fuel-supply receptacles, a main fuel pump having its suction side connected to either of said receptacles, a reserve fuel-supply container, an electric motor driven auxiliary fuel pump having its suction side connected to said contaainer, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, and the main fuel pump being adapted to deliver fuel at a higher pressure than the auxiliary fuel pump, a check valve adapted to. prevent flow from the discharge side of said main fuel pump to the discharge side of said auxiliary fuel pump, a pressure responsive switch associated with the main fuel pump, adapted, upon a predetermined drop in pressure at the discharge side of the main fuel pump, due to a receptacle to which its suction side is connected being empty, to close and direct an electric current to operate said electric motor driven auxiliary fuel pump, and electromagnetic means operative by said switch, upon closing, to disconnect the suction side of the main fuel pump from the empty receptacle and connect it to a full receptacle, whereby said main fuel pump may provide said predetermined pressure to open said pressure operated switch to stop said electric motor driven auxiliary pump.

4. The combination, in an aircraft fuel system, of a main fuel supply receptacle, a main fuel pump havin its suction side connected to said main fuel supply receptacle, a reserve fuel supply container, an auxiliary fuel pump having its suction side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, and a fuel pressure responsive means associated with the main fuel pump, adapted, upon a predetermined drop in pressure at the discharge side of the main fuel pump to operate said auxiliary fuel pump.

5. The combination, in an aircraft fuel system, of a main fuel supply receptacle, a main fuel pump having its suction side connected to said main fuel supply receptacle, a reserve fuel supply container, an auxiliary fuel pump having its suction side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, and a pressure responsive means associated with the main fuel pump, adapted, upon a drop in pressure at the discharge side of the main fuel pump to a pressure slightly above the discharge pressure capacity of the auxiliary fuel pump to operate said auxiliary fuel pump, whereby restoration of the discharge pressure of the main fuel pump is required to stop the auxiliary fuel pump.

6. The combination, in an aircraft fuel system, of a main fuel supply receptacle, a. main fuel pump having its suction side connected to said main fuel supply receptacle, a reserve fuel supply container, an auxiliary fuel pump having its suc- 55 tion side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, each pump being adapted to maintain a predetermined discharge pressure, 0 the predetermined discharge pressure of the main pump being higher than that of the auxiliary pump, and a pressure responsive means associated with the main fuel pump, adapted, upon a predetermined drop at the discharge side of the 65 main fuel pump to a pressure between the discharge pressures of the two said pumps to operate said auxiliary fuel pump, whereby restoration of the main pump to its predetermined pressure capacity will stop operation of the auxiliary pump.

'7. The combination, in an aircraft fuel system, of an engine, a main .fuel supply receptacle, an engine driven fuel pump havin its suction side connected to said main fuel supply receptacle, 75 a reserve fuel supply container, an electrically driven fuel pump having its suction side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, each pump being adapted to maintain a predetermined discharge pressure, the predetermined discharge pressure of the engine driven pump being higher than that of the electrically driven pump, and a pressure responsive electric switch associated with the main fuel pump, adapted, upon a predetermined drop at the discharge side of the main fuel pump to a pressure between the discharge pressures of the two said pumps to operate said auxiliary fuel pump, whereby restoration of the engine driven pump to its predetermined pressure capacity will stop operation of the electrically driven pump.

8. The combination, in an aircraft fuel system, of an engine, a main fuel supply receptacle, an engine driven fuel pump having its suction side connected to said main fuel supply receptacle, a reserve fuel supply container, an electrically driven fuel pump having its suction side connected to said reserve fuel supply container, a fuel receiving means, the discharge side of both said pumps being connected to said fuel receiving means, the engine driven pump being arranged to maintain a predetermined discharge pressure and the electrically driven pump being arranged to maintain a lesser discharge pressure than the engine driven pump, a pressure responsive electric switch connected to the discharge side of the main fuel pump, adapted, upon a drop at the discharge side of the main fuel pump to a pressure 10 which is between the discharge pressures of the two pumps to operate said electrically driven pump, and a check valve interposed between the discharge sides of the two pumps biased to prevent fiow from the discharge side of the engine driven pump to the discharge side of the electrically driven pump.

9. The combination, in an aircraft fuel system, of an engine, a plurality of main fuel supply receptacles, an engine driven pump having its suction side connected to either of said main fuel supply receptacles, a reserve fuel supply container, an electrically driven pump having its suction sideconnected to said reserve fuel supply container, a fuel receiving means, the discharge sides of both pumps being connected to said fuel receiving means, the engine driven pump being arranged to maintain a given discharge pressure and the electrically driven pump being arranged to maintain a lower discharge pressure than the engine driven pump, a pressure responsive electric switch connected to the discharge side of the engine driven pump, adapted upon a drop at the discharge side of the engine driven pump, to a pressure which is between the discharge pressures of the two said pumps, to operate said electrically driven pump and electromagnetic means operative coincidentally with said pressure responsive electric switch to disconnect one main fuel supply receptacle from the suction side of the engine driven pump and connect another main fuel supply receptacle thereto.

DAVID SAMlRAN. 

